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G. L. Soderberg - One of the best experts on this subject based on the ideXlab platform.
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The effect of Muscle Length on motor unit discharge characteristics in human tibialis anterior Muscle.
Experimental Brain Research, 1991Co-Authors: D. W. Vander Linden, Carl G Kukulka, G. L. SoderbergAbstract:Muscle Length influences the contractile properties of Muscle in that when Muscle is Lengthened the relaxation phase of the Muscle twitch is prolonged and when Muscle is shortened, the relaxation phase is shorter in duration. As a result, the force exerted by active motor units varies with Muscle Length during voluntary contractions. To determine if motoneuron spike trains were adjusted to accommodate for changes in the contractile properties imposed by shortened and Lengthened Muscle, motor unit action potentials were recorded from the tibialis anterior Muscle at different Muscle Lengths. Twenty subjects performed isometric ramp contractions at ankle angles of 20° dorsiflexion, neutral between dorsiflexion and plantar flexion, and 30° plantar flexion, which put the tibialis anterior Muscle in a shortened, neutral, or Lengthened condition, respectively. During isometric contractions where torque increased at 5% MVC/s, motor unit discharge rate at recruitment was greater in shortened Muscle than in Lengthened Muscle (P
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the effect of Muscle Length on motor unit discharge characteristics in human tibialis anterior Muscle
Experimental Brain Research, 1991Co-Authors: D Vander W Linden, Carl G Kukulka, G. L. SoderbergAbstract:Muscle Length influences the contractile properties of Muscle in that when Muscle is Lengthened the relaxation phase of the Muscle twitch is prolonged and when Muscle is shortened, the relaxation phase is shorter in duration. As a result, the force exerted by active motor units varies with Muscle Length during voluntary contractions. To determine if motoneuron spike trains were adjusted to accommodate for changes in the contractile properties imposed by shortened and Lengthened Muscle, motor unit action potentials were recorded from the tibialis anterior Muscle at different Muscle Lengths. Twenty subjects performed isometric ramp contractions at ankle angles of 20° dorsiflexion, neutral between dorsiflexion and plantar flexion, and 30° plantar flexion, which put the tibialis anterior Muscle in a shortened, neutral, or Lengthened condition, respectively. During isometric contractions where torque increased at 5% MVC/s, motor unit discharge rate at recruitment was greater in shortened Muscle than in Lengthened Muscle (P<0.05). Brief initial interspike intervals (<40 ms) occurred more frequently in shortened Muscle than in either neutral Length or Lengthened Muscle. During steady contractions, motor unit discharge rate was greater per unit torque (N.m) in shortened Muscle than in neutral Length or Lengthened Muscle (P<0.05). These findings indicate that Muscle Length does influence the discharge pattern of motor unit spike trains during isometric ramp contractions. Spike trains with higher discharge rates at recruitment in shortened Muscle may take advantage of the catch-like properties in Muscle and be useful in taking up the slack in the passive elements of the Muscle and tendon. During steady submaximal contractions, the higher discharge rate per unit torque (N.m) in shortened Muscle is likely due to the decreased peak tension and shorter one-half relaxation time observed in shortened Muscle, and may indicate that the tibialis anterior Muscle is operating on the steep portion of the Length-tension curve when the ankle is fully dorsiflexed.
Sébastien Ratel - One of the best experts on this subject based on the ideXlab platform.
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Effect of Muscle Length on voluntary activation of the plantar flexors in boys and men.
European journal of applied physiology, 2016Co-Authors: Virginie Kluka, Vincent Martin, Sebastian Garcia Vicencio, Mathias Giustiniani, Claire Morel, Cédric Morio, Emmanuel Coudeyre, Sébastien RatelAbstract:Purpose The aim of the present study was to compare the effect of Muscle Length on the maximal voluntary activation level (VA) of the plantar-flexors between children and adults.
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Effect of Muscle Length on voluntary activation of the plantar flexors in boys and men
European Journal of Applied Physiology, 2016Co-Authors: Virginie Kluka, Vincent Martin, Sebastian Garcia Vicencio, Mathias Giustiniani, Claire Morel, Cédric Morio, Emmanuel Coudeyre, Sébastien RatelAbstract:The aim of the present study was to compare the effect of Muscle Length on the maximal voluntary activation level (VA) of the plantar-flexors between children and adults. Fourteen boys (10.0 ± 1.0 years) and fifteen men (24.6 ± 4.2 years) performed 5-s maximal isometric voluntary contractions (MVC) of the plantar-flexor Muscles at seven ankle angles [from 10° in dorsi-flexion (DF) to 20° in plantar-flexion (PF); 0° = reference position; the angle between the plantar surface and leg is a right angle]. Single magnetic stimulations were delivered to the posterior tibial nerve during MVCs to determine VA. Results showed a higher absolute torque of the plantar-flexor Muscles at long (10° DF) than at short Muscle Length (20° PF) in men (89.4 ± 19.4 vs. 46.8 ± 17.0 N m, P < 0.001) and boys (44.9 ± 18.5 vs. 26.6 ± 12.8 N m, P < 0.001). On average, VA was significantly higher in men than in boys (92.4 ± 1.7 vs. 87.6 ± 1.6 %, P < 0.05). However, no significant main effect of the ankle angle was observed on VA. The VA partly accounts for the plantar-flexors MVC torque difference between children and adults but is not affected by the Muscle Length changes in both groups. Therefore, VA cannot account for the shape of the torque–angle relationship on the plantar-flexor Muscles
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Effect of Muscle Length on voluntary activation level in children and adults.
Medicine and science in sports and exercise, 2015Co-Authors: Virginie Kluka, Vincent Martin, Sebastian Garcia Vicencio, Cédric Morio, Emmanuel Coudeyre, Anne-gaëlle Jegu, Charlotte Cardenoux, Sébastien RatelAbstract:AB Purpose: The aim of the present study was to compare the effect of Muscle Length on the level of voluntary activation (VA) at short and long Muscle Lengths between children and adults. Methods: Thirteen prepubertal boys (10.2 +/- 1.1 yr) and 10 men (23.9 +/- 2.9 yr) performed 5-s maximal isometric voluntary contractions of the knee extensor Muscles at three muscular angles (20[degrees], 90[degrees], 100[degrees]; 0[degrees], full extension) interspersed with at least 60-s passive recovery periods. Single magnetic stimulations were delivered to the femoral nerve during maximal isometric voluntary contractions to determine the level of VA using the twitch interpolation technique. The specific torque was calculated as the absolute torque divided by thigh Muscle mass, as assessed using dual-energy x-ray absorptiometry. Finally, the theoretical specific torque that could be produced with a complete (i.e., 100%) activation level (specific torque at 100% VA) was estimated from the values of specific torque and VA. Results: Results showed a higher specific torque in adults at 90[degrees] and 100[degrees] but not at 20[degrees]. Accordingly, VA was significantly higher in adults at 90[degrees] (94% +/- 4% vs 88% +/- 8%, P < 0.05) and 100[degrees] (93% +/- 6% vs 86% +/- 8%, P < 0.05), whereas no significant difference was observed at 20[degrees]. Interestingly, the specific torque at 100% VA was not different between groups whatever the joint angle. Conclusions: The lower ability of children to fully activate their motor units at long Muscle Length could account for their lower specific torque because no difference in theoretical specific torque was observed between groups at 90[degrees] and 100[degrees]
Carl G Kukulka - One of the best experts on this subject based on the ideXlab platform.
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Relationship between Muscle Length and moment arm on EMG activity of human triceps surae Muscle
Journal of electromyography and kinesiology : official journal of the International Society of Electrophysiological Kinesiology, 2004Co-Authors: Mohammad Reza Nourbakhsh, Carl G KukulkaAbstract:Abstract Purpose : The purpose of this experiment was to evaluate the effects of both Muscle Length and moment arm (MA) on the electromyographic (EMG) and force output of the triceps surae (TS) Muscle. Relevance : It is well recognized that changes in Muscle Length affect both the Muscle's force generating capacity as well as its twitch speed. This relationship is well established in animal preparations. Contrary to animal experiments where Length can be directly manipulated in isolated Muscles, human experiments require that all Muscle Length changes be secondary to changes in a joint angle. Such experimental manipulations therefore produce changes in not only Muscle Length, but also in the Muscle's MA. The relative effect of Muscle Length and MA changes on Muscle EMG has not been determined in previous experiments. Method : This study was executed in two phases. First, using fresh human cadaver lower limbs, data were gathered describing the relationship between knee and ankle angle changes for maintenance of a constant TS Muscle Length, while its MA at the ankle joint has been changed. In the second phase of the study, results obtained from phase one were applied to 10 healthy adult human subjects to measure the EMG (surface and fine wire) activity of TS at three different conditions: when both Length and MA were shortened, when Muscle Length was decreased given a constant MA and when MA was shortened given a constant Muscle Length. Results : A significant increase in Muscle activity was found as both the Length and MA of TS Muscle were shortened. A similar pattern of increased Muscle activity was observed when the MA was shortened given a constant Muscle Length. No significant change in TS activity was found when Muscle Length was shortened, given a constant MA at the ankle joint. Conclusion : The findings of this study indicate that changes in the Achilles tendon MA predominate over the Muscle Length variations in determining the level of TS activity when generating plantar flexion torque.
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The effect of Muscle Length on motor unit discharge characteristics in human tibialis anterior Muscle.
Experimental Brain Research, 1991Co-Authors: D. W. Vander Linden, Carl G Kukulka, G. L. SoderbergAbstract:Muscle Length influences the contractile properties of Muscle in that when Muscle is Lengthened the relaxation phase of the Muscle twitch is prolonged and when Muscle is shortened, the relaxation phase is shorter in duration. As a result, the force exerted by active motor units varies with Muscle Length during voluntary contractions. To determine if motoneuron spike trains were adjusted to accommodate for changes in the contractile properties imposed by shortened and Lengthened Muscle, motor unit action potentials were recorded from the tibialis anterior Muscle at different Muscle Lengths. Twenty subjects performed isometric ramp contractions at ankle angles of 20° dorsiflexion, neutral between dorsiflexion and plantar flexion, and 30° plantar flexion, which put the tibialis anterior Muscle in a shortened, neutral, or Lengthened condition, respectively. During isometric contractions where torque increased at 5% MVC/s, motor unit discharge rate at recruitment was greater in shortened Muscle than in Lengthened Muscle (P
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the effect of Muscle Length on motor unit discharge characteristics in human tibialis anterior Muscle
Experimental Brain Research, 1991Co-Authors: D Vander W Linden, Carl G Kukulka, G. L. SoderbergAbstract:Muscle Length influences the contractile properties of Muscle in that when Muscle is Lengthened the relaxation phase of the Muscle twitch is prolonged and when Muscle is shortened, the relaxation phase is shorter in duration. As a result, the force exerted by active motor units varies with Muscle Length during voluntary contractions. To determine if motoneuron spike trains were adjusted to accommodate for changes in the contractile properties imposed by shortened and Lengthened Muscle, motor unit action potentials were recorded from the tibialis anterior Muscle at different Muscle Lengths. Twenty subjects performed isometric ramp contractions at ankle angles of 20° dorsiflexion, neutral between dorsiflexion and plantar flexion, and 30° plantar flexion, which put the tibialis anterior Muscle in a shortened, neutral, or Lengthened condition, respectively. During isometric contractions where torque increased at 5% MVC/s, motor unit discharge rate at recruitment was greater in shortened Muscle than in Lengthened Muscle (P<0.05). Brief initial interspike intervals (<40 ms) occurred more frequently in shortened Muscle than in either neutral Length or Lengthened Muscle. During steady contractions, motor unit discharge rate was greater per unit torque (N.m) in shortened Muscle than in neutral Length or Lengthened Muscle (P<0.05). These findings indicate that Muscle Length does influence the discharge pattern of motor unit spike trains during isometric ramp contractions. Spike trains with higher discharge rates at recruitment in shortened Muscle may take advantage of the catch-like properties in Muscle and be useful in taking up the slack in the passive elements of the Muscle and tendon. During steady submaximal contractions, the higher discharge rate per unit torque (N.m) in shortened Muscle is likely due to the decreased peak tension and shorter one-half relaxation time observed in shortened Muscle, and may indicate that the tibialis anterior Muscle is operating on the steep portion of the Length-tension curve when the ankle is fully dorsiflexed.
D Vander W Linden - One of the best experts on this subject based on the ideXlab platform.
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the effect of Muscle Length on motor unit discharge characteristics in human tibialis anterior Muscle
Experimental Brain Research, 1991Co-Authors: D Vander W Linden, Carl G Kukulka, G. L. SoderbergAbstract:Muscle Length influences the contractile properties of Muscle in that when Muscle is Lengthened the relaxation phase of the Muscle twitch is prolonged and when Muscle is shortened, the relaxation phase is shorter in duration. As a result, the force exerted by active motor units varies with Muscle Length during voluntary contractions. To determine if motoneuron spike trains were adjusted to accommodate for changes in the contractile properties imposed by shortened and Lengthened Muscle, motor unit action potentials were recorded from the tibialis anterior Muscle at different Muscle Lengths. Twenty subjects performed isometric ramp contractions at ankle angles of 20° dorsiflexion, neutral between dorsiflexion and plantar flexion, and 30° plantar flexion, which put the tibialis anterior Muscle in a shortened, neutral, or Lengthened condition, respectively. During isometric contractions where torque increased at 5% MVC/s, motor unit discharge rate at recruitment was greater in shortened Muscle than in Lengthened Muscle (P<0.05). Brief initial interspike intervals (<40 ms) occurred more frequently in shortened Muscle than in either neutral Length or Lengthened Muscle. During steady contractions, motor unit discharge rate was greater per unit torque (N.m) in shortened Muscle than in neutral Length or Lengthened Muscle (P<0.05). These findings indicate that Muscle Length does influence the discharge pattern of motor unit spike trains during isometric ramp contractions. Spike trains with higher discharge rates at recruitment in shortened Muscle may take advantage of the catch-like properties in Muscle and be useful in taking up the slack in the passive elements of the Muscle and tendon. During steady submaximal contractions, the higher discharge rate per unit torque (N.m) in shortened Muscle is likely due to the decreased peak tension and shorter one-half relaxation time observed in shortened Muscle, and may indicate that the tibialis anterior Muscle is operating on the steep portion of the Length-tension curve when the ankle is fully dorsiflexed.
Virginie Kluka - One of the best experts on this subject based on the ideXlab platform.
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Effect of Muscle Length on voluntary activation of the plantar flexors in boys and men.
European journal of applied physiology, 2016Co-Authors: Virginie Kluka, Vincent Martin, Sebastian Garcia Vicencio, Mathias Giustiniani, Claire Morel, Cédric Morio, Emmanuel Coudeyre, Sébastien RatelAbstract:Purpose The aim of the present study was to compare the effect of Muscle Length on the maximal voluntary activation level (VA) of the plantar-flexors between children and adults.
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Effect of Muscle Length on voluntary activation of the plantar flexors in boys and men
European Journal of Applied Physiology, 2016Co-Authors: Virginie Kluka, Vincent Martin, Sebastian Garcia Vicencio, Mathias Giustiniani, Claire Morel, Cédric Morio, Emmanuel Coudeyre, Sébastien RatelAbstract:The aim of the present study was to compare the effect of Muscle Length on the maximal voluntary activation level (VA) of the plantar-flexors between children and adults. Fourteen boys (10.0 ± 1.0 years) and fifteen men (24.6 ± 4.2 years) performed 5-s maximal isometric voluntary contractions (MVC) of the plantar-flexor Muscles at seven ankle angles [from 10° in dorsi-flexion (DF) to 20° in plantar-flexion (PF); 0° = reference position; the angle between the plantar surface and leg is a right angle]. Single magnetic stimulations were delivered to the posterior tibial nerve during MVCs to determine VA. Results showed a higher absolute torque of the plantar-flexor Muscles at long (10° DF) than at short Muscle Length (20° PF) in men (89.4 ± 19.4 vs. 46.8 ± 17.0 N m, P < 0.001) and boys (44.9 ± 18.5 vs. 26.6 ± 12.8 N m, P < 0.001). On average, VA was significantly higher in men than in boys (92.4 ± 1.7 vs. 87.6 ± 1.6 %, P < 0.05). However, no significant main effect of the ankle angle was observed on VA. The VA partly accounts for the plantar-flexors MVC torque difference between children and adults but is not affected by the Muscle Length changes in both groups. Therefore, VA cannot account for the shape of the torque–angle relationship on the plantar-flexor Muscles
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Effect of Muscle Length on voluntary activation level in children and adults.
Medicine and science in sports and exercise, 2015Co-Authors: Virginie Kluka, Vincent Martin, Sebastian Garcia Vicencio, Cédric Morio, Emmanuel Coudeyre, Anne-gaëlle Jegu, Charlotte Cardenoux, Sébastien RatelAbstract:AB Purpose: The aim of the present study was to compare the effect of Muscle Length on the level of voluntary activation (VA) at short and long Muscle Lengths between children and adults. Methods: Thirteen prepubertal boys (10.2 +/- 1.1 yr) and 10 men (23.9 +/- 2.9 yr) performed 5-s maximal isometric voluntary contractions of the knee extensor Muscles at three muscular angles (20[degrees], 90[degrees], 100[degrees]; 0[degrees], full extension) interspersed with at least 60-s passive recovery periods. Single magnetic stimulations were delivered to the femoral nerve during maximal isometric voluntary contractions to determine the level of VA using the twitch interpolation technique. The specific torque was calculated as the absolute torque divided by thigh Muscle mass, as assessed using dual-energy x-ray absorptiometry. Finally, the theoretical specific torque that could be produced with a complete (i.e., 100%) activation level (specific torque at 100% VA) was estimated from the values of specific torque and VA. Results: Results showed a higher specific torque in adults at 90[degrees] and 100[degrees] but not at 20[degrees]. Accordingly, VA was significantly higher in adults at 90[degrees] (94% +/- 4% vs 88% +/- 8%, P < 0.05) and 100[degrees] (93% +/- 6% vs 86% +/- 8%, P < 0.05), whereas no significant difference was observed at 20[degrees]. Interestingly, the specific torque at 100% VA was not different between groups whatever the joint angle. Conclusions: The lower ability of children to fully activate their motor units at long Muscle Length could account for their lower specific torque because no difference in theoretical specific torque was observed between groups at 90[degrees] and 100[degrees]
